The addon app does not seem to be working on the cloud version.
the inputs section just sits on loading.
Per the Splunk Cloud Service Description, inputs on the search head are not allowed: http://docs.splunk.com/Documentation/SplunkCloud/latest/Service/SplunkCloudservice#Differences_betwe...
This could be the reason why the inputs screen sits on loading.
Your best course of action here would be to leverage an on-prem box as the input box, I currently have it working on our syslog collector which is a Heavy Forwarder on-prem. We had to update the firewall rules to allow the traffic out. Or you can spin up a VM in AWS, install splunk on that and configure the inputs from there. We find the first method useful for other inputs that are not supported on our Splunk Cloud search head
Per the Splunk Cloud Service Description, inputs on the search head are not allowed: http://docs.splunk.com/Documentation/SplunkCloud/latest/Service/SplunkCloudservice#Differences_betwe...
This could be the reason why the inputs screen sits on loading.